Winterizing glyceride oils



United States Patent C) Pennsylvania No Drawing. Filed May 9, 1962, Ser. No. 193,606

Claims. or. 260428) This invention relates to the removal by centrifugal force of higher melting substances from glyceride oils. More specifically this invention relates to Winterizing vegetable oils and the like.

For many years it has been a problem in the production of vegetable oils and the like that such oils upon being exposed to lower temperatures in the household refrigerator, for instance, become cloudy and are therefore unattractive to the housewife. Prior attempts have been made to eliminate the tendency of such oils to form a cloud at lower temperatures. These attempts to accomplish such Winterizing have generally involved chilling the oil to a temperature of, for instance, 45 F. or below over a period of 3 /2 to 5 days, during which time crystals or other solids of higher melting substances called stearine which cause the objectionable cloud slowly form, grow and agglomerate. From the cell the mixture including the oil and solids has been forced through a filter press in a painstakingly slow process in which the solids, due to their large particle size, are removed from the oil.

In his application Serial No. 140,092, filed in the US. Patent Ofiice on September 22, 1961, now Patent No. 3,145,223, and assigned to my assignee, Thomas H. Little has described a process whereby Winterizing of vegetable oils and the like may be accomplished by centrifugal force. This process has had the advantage over filter press operation that the chilling may be effected in a relatively short period of time, e.g. two days, wherein higher melting substances, e.g. stearine, have crystalized or otherwise solidified to the extent necessary, and the mixture including the solids is delivered to a centrifuge. A suitable centrifuge may be a type having peripheral automatic valves as described in Patent 2,286,- 354 or 2,286,355 to Fitzsimmons. The speed-up in the chilling process over the conventional filter press winterizing process is attributable to the fact that for separation by centrifugal force there need be developed only a difference in specific gravity between the solid portions and the oil, and large particle size is not necessary.

My present invention may be regarded as an improvement over the process described in the aforementioned patent application. The invention of the earlier application is a considerable advance over the filter press method of Winterizing and is indeed surprising and inventive since among other things it demonstrates that contrary to what one would otherwise think, solid portions in the chilled glyceride oils, e.g. cottonseed oil, may be extruded through peripheral openings in a centri fuge. My invention is predicated on my discovery in centrifugal Winterizing that glyceride oils, such as cottonseed oil in the absence of a solvent, may be eifectively winterized to effect improved cold tests by super cooling to a temperature not above 40 F. and preferably between 30 and 35 F. by rapidly moving it through a chilling zone after its initial cooling and immediately prior to centrifuging.

This improvement of my invention will be unexpected to those skilled in the art since it has been believed that oils such as glyceride will form an unworkable gel at temperatures 40 F. and below. It has also been thought that for improving cold test, reduction of temperature must be accompanied by absolute stillness. I have found erably in a range between 30 and 35 cooling zone may take the form of a conventional shelland-tube chiller wherein brine or the like circulates be 3,173,936 Patented Mar. 16, 1965 that appreciable increase in viscosity and formation of a gel may be avoided in processing such oil to 40 F. and below if the oil is continuously and rapidly moved through the super cooling zone and that such super cooling though accomplished quickly while the oil is in movement gives marked improvement in cold test readings after centrifuging.

Briefly, in a process for Winterizing glyceride oils including the steps of chilling the oil at least partly in relative quiescence to crystalize or otherwise solidify higher melting portions thereof and centrifuging to separate the winterized oil and the solid portions, the invention is the improvement of super cooling the chilled oil with solid portions by moving it rapidly through a super cooling zone to reduce its temperature to at least about 40 F., and preferably between 35 F. and 30 F., and then immediately effecting said centrifuging.

In a process embodying the invention and illustrative thereof, a supply of summer oil, such as unwinterized cottonseed oil, is delivered to a cooling cell. A conventional cell, well known in the prior art, may be rectangular in shape and have a capacity of 60,000 pounds of oil. Brine or other cooling agent circulates through heat exchange surfaces in the cell. Over a period of time which'may vary up to about five days, the temperature of the oil in the cell is gradually brought down from the initial temperature of perhaps to, for instance, 45 to 50 F. At infrequent intervals air may be gently bubbled from pipes at the bottom of the cell upward through the oil to roll the oil over and facilitate its cooling. Alternatively, a slow-moving agitator may be used to very gently roll the oil about the cell. It is believed that in addition to facilitating cooling, such gentle air agitation and/or mechanical agitation promotes uniformity in crystal or solids.

In this relatively quiescent condition at temperatures These solids which in the art are called stearine are saturated fats and are higher-melting substances which it is desired to remove from the oil.

From the cell the oil with its solidified portions is in accordance with my process conducted through a zone of super cooling to lower the temperature at least 5, preferably at least 10 F., to 40 F. or below and pref F. The supertween the shell and the tubes and the oil is conducted through the tubes or alternatively it may be a Votator. The latter device comprises a chamber having coolant jacketed walls with its inner walls which are contacted by the oil flowing through wiped by a rotor.

From the super-cooling zone comprising the shell-andtube cooler or any equipment device through which the oil may be rapidly moved to decrease its temperature quickly by at least 5 the oil with solidified portions is delivered to a zone of centrifuging. The zone of centrifuging is, in the preferred embodiment, a centrifuge having automatically opened peripheral valves as under one of the above patents and available under the trademark Autojector. The operation of such a centrifuge in separating stearine from oil is thoroughly discussed in the above-identified application of Thomas H. Little. The stearine, of greater density than the oil as it accumulates, is periodically discharged through openings in the periphery of the centrifuge, and the oil having stearine removed is discharged from a position inward of the periphery. The valve-operating liquid may be collected separately.

In another embodiment in accordance with the process 'of my invention the initial cooling cell is replaced by a continuous chilling device such as a shell-and-tube chiller or Votator and a cooling tank adapted to receive the. cooled oil from the shel-l-and-tube chiller or the Vot'ator. In the cooling'tank the oil is subjected fora number of hours to relative quiescence which may be occasionally "mildly disturbed 'by a slowly rotating agitator or by bubbling air through the tank to roll over the dil and facilitate temperature equilibrium and crystal formation and/ or growth;

In an arrangement embodying the process of my invention a 60,'000# .cell is followed by a she'll-and-tube chiller and then an Autojector centrifuge. Summer or unwinterized cottonseed oil was delivered to the cell and the temperature was gradually brought down over a period several days with occasional mild agitation to 49 F. 'From the Winterizing cell the oil having solidified portions was continuously led through a shell-and-t-ube chiller wherefrom it discharged at a temperature of 32". At' the rate of 2500 pounds/hour the discharge was led to the centrifuge having an 18" radius and rotating at approximately 6200 r.p.m. and the separated winterized oil was characterized bya cold test of 13.6 hours.

From a similar cell oil similarly cooled and having solidified portions therein at a temperature of 49 was delivered directly to the same centrifuge. Even though the rate at which the cooled oil was delivered was slower, 2000 pounds/hour, the separated winterized oil had a cold test or 9.5 hours.

As used herein the term glyceride oi includes vegetable oils such as cottonseed oil, peanut-oil, soybean oil, and oils derived from animal and marine sources, such as, fish oil. JTheinvention may also be utilized on oils synthetically produced as in the case of oils produced by hydrogenation and/or molecular rearrangement.

The term winterize originated according to A. E.

Bailey 'in' Industrial Oil & Fat Products. (1945) in that the "separation was originally carried out by allowing oil to stand outside and settle out in the wintertime. winterizing is used herein to include both the refrigeration an'dthe separation of the solid portions from the oil as well 'asjust the refrigerating. Hence winterized oi refers to oil after the separation of the solids portions therefrom or to that portion of the-chilled .oil-solidportions, mixture aside from the solid. portions.

' It will be understood by one skilled in the art that the description herein omits for simplicity the provision of necessary pumps, valves and other-fittings which would be necessary or desirable in the practice of the invention. It will further be understood" that it is by way of illustration and not of limitation, and that changes,-omissions, additions, substitutions and/or other modifications may be made without departing from the spirit thereof. Accordingly it is intended that the patent shall cover by suitable expression in the claims the various features of patentable novelty that reside in the invention.

1. In a process for Winterizing glyceride oils including the steps of chillingthe oil atleast partly in relative quiescence to solidify higher melting substances therein and centrifuging to separate the winterized oil and the solidified portions, the improvement of super cooling the chilled oil with solid portions by moving it rapidly through a super-cooling zone to reduce its temperature to at least about 40 F., and then immediately effecting said centrifuging.

2. The process of claim 1 wherein the super-cooling 7 zone reduces the temperature to between about 35 and 3. The process of claim 2 wherein the glyceride oil is cottonseed oil.

4. In a process for Winterizing glyeeride oil including the steps of chilling the oil at least partly while it is in a condition of relative quiescence to solidfy higher melting substances therein, delivering the winterized oil and the solidified portionsto a zone. of centrifuging, forming a layer of the solidified portions at the periphery of the zone of centrifuging'and a' layer of separated oil inside the layer of the solidified portions, discharging the separated winterized oil from a locus inward of the periphery of the zone of centrifuging and discharging periodically-at least a portion of the accumulated solidified portions layer through the periphery of the zone of centrifuging; the improvement of super cooling the chilled oil with solidified portions by moving it rapidly througha super-cooling zone to quickly reduce its'temperature by at least 5 to about 40 vF. or below, and then immediately etfecting said centrifuging.

5. The process of claim 4 wherein the oil is cottonseed oil, and the temperature is quickly reduced by at leastl0 F. to between 30 and 35 F.

References Cited by the Examiner UNIT-ED STATES PATENTS 2,205,381 6/40 Eckey et al. 260428 2,286,354 6/42 Fitzsimmons 23320 2,286,355 6/42 Fitzsimmons 23320 2,425,001 8/47 Parkin et a1. 260-428 2,435,626 2/48 Gooding et al. 260-428 X 2,610,915 9/52 Mattil 260--428 X CHARLES i B. PARKER, Primary Examiner. 

1. IN A PROCESS FOR WINTERIZING GLYCERIDE OILS INCLUDING THE STEPS OF CHILLING THE OIL AT LEAST PARTLY IN RELATIVE QUIESCENCE TO SOLIDIFY HIGHER MELTING SUBSTANCES THEREIN AND CENTRIFUGING TO SEPARATE THE WINTERIZED OIL AND THE SOLIDIFIED PORTIONS, THE IMPROVEMENT OF SUPER COOLING THE CHILLED OIL WITH SOLID PORTIONS BY MOVING IT RAPIDLY THROUGH A SUPER-COOLING ZONE TO REDUCE ITS TEMPERATURE TO AT LEAST ABOUT 40*F., AND THEN IMMEDIATELY EFFECTING SAID CENTRIFUGING. 